Lectins, such as wheat germ agglutinin and Concanavalin A, the agglutinate transformed cells more effectively than normal cells presumably bind to a spectrum of glyco-protein and glycolipid receptor sites on both normal and transformed cells. There are several possible explanations for the specific agglutinability of transformed cells, and one of them is that there exists among the spectrum of binding sites on transformed cells a very small percentage of transformation-specific high affinity sites that are not among the spectrum of binding sites on normal cells. As long as the percentage of the specific sites is small, the total number of lectin binding sites will be similar on normal and transformed cells. The proposed research is aimed at testing this explanation, at determining the chemical nature of the tumor-specific lectin binding sites, and at incorporating these structures into synthetic antigens designed to elicit an immune response with even greater specificity for transformed cells than the original lectin. To date the structure implied by the specificity of wheat germ agglutinin has been incorporated into a glycoprotein antigen which has been shown to function like a tumor-specific transplantation antigen. The modes of action of this antigen and an equally effective analog are being examined.